I need to replace the halon extinguishers in a 435 Princess. There doesn't seem to be much information on the internet on various options other than dry powder is a bad idea (horrible mess and damages the engines - annoying if it goes off by accident!).
I have seen the Stat X solid aerosol recommended in one of the boat magazines and spoke to someone about it at the boat show. He indicated that a system for around 10 cu M would be around £1,800 incl fitting and vat (around £500 for the extinguisher, £500 for the alarm / contoller / sensors and £500 fitting). This would give a system which would be automatic when not on board, but would set off an alarm when at sea with a manual firing option (i.e. allowing you to shut down the engines and bilge fan when safe to do so and to stop the gas being sucked through the engines). The extinguisher is an aerosol type with a 10 year service life and there is a certain logic to setting it up in the way described. The Stat X website in the States appears to only show the extinguisher units themselves rather than the heat sensors / controllers / alarms - so these are presumably from another supplier but I can find no information on such things on the internet.
A cheaper (simpler, but probably more compromised) route would seem to be a 6KG Fireblitz FBA G6 Clean Agent Gas extinguisher which I could buy for around £400 and fit myself. The service life is around 5 years, but it would be temperature activated and would be ineffective if the engines are not shut down before it activates (which is quite likely in reality). In principle of operation it is similar to the two (banned) halon extinguishers currently mounted over the engines, but would in theory be more effective as it is a single extinguisher - so should deliver the full volume gas in one go (as opposed to one going off, being ineffective as insufficient gas to flood the engine bay and then the second going off when the fire reignites and suffering the same problem).
I'm surprised that there is so little information available on systems and options as this must be an area of high turnover (lots of boats and extinguishers with relatively short service lives). Any thoughts, recommendations or references to useful articles would be much appreciated as the Fireblitz option doesn't really sound the way to go (although presumably they sell alot of them).